Method and system for arc suppression in a plasma processing system

ABSTRACT

An arc suppression system for plasma processing comprising at least one sensor coupled to the plasma processing system, and a controller coupled to the at least one sensor. The controller provides at least one algorithm for determining a state of plasma in contact with a substrate using at least one signal generated from the at least one sensor and controlling a plasma processing system in order to suppress an arcing event. When voltage differences between sensors exceed a target difference, the plasma processing system is determined to be susceptible to arcing. During this condition, an operator is notified, and decision can be made to either continue processing, modify processing, or discontinue processing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Application Ser. No.60/391,950, filed Jun. 28, 2002; and this application is related to U.S.Pat. No. 6,332,961, entitled “Device and method for detecting andpreventing arcing in RF plasma systems,” the entire contents of whichare incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to plasma processing and more particularlyto an arc suppression system for plasma processing and a method of usingthereof.

2. Discussion of the Background

The fabrication of integrated circuits (IC) in the semiconductorindustry typically employs plasma to create and assist surface chemistrywithin a plasma reactor necessary to remove material from and depositmaterial to a substrate. In general, plasma is formed within the plasmareactor under vacuum conditions by heating electrons to energiessufficient to sustain ionizing collisions with a supplied process gas.Moreover, the heated electrons can have energy sufficient to sustaindissociative collisions and, therefore, a specific set of gases underpredetermined conditions (e.g., chamber pressure, gas flow rate, etc.)are chosen to produce a population of charged species and chemicallyreactive species suitable to the particular process being performedwithin the chamber (e.g., etching processes where materials are removedfrom the substrate or deposition processes where materials are added tothe substrate). Typically, during plasma processing such as etchapplications, it is likely that electric charge will accumulate acrossthe substrate surface. However, it is possible that the substratecharging can be spatially non-homogeneous across the substrate surface.The non-homogeneous charging of the substrate surface has been observedto arise due to a spatially non-homogeneous plasma overlying and incontact with the substrate surface. The plasma non-homogeneity can beattributed to, for example, non-uniform plasma generation or lossresulting in a non-uniform plasma density, or a non-uniform plasmasheath overlying the substrate surface associated with the plasmareactor structure surrounding the substrate resulting in a non-uniformion energy (for ions striking the substrate surface). As a consequenceof these non-homogeneities, the risk of lateral arcing across thesubstrate is greatly enhanced. Substrate arcing must be avoided entirelyin order to preserve acceptable device yield.

SUMMARY OF THE INVENTION

The present invention provides an arc suppression system for a plasmaprocessing system comprising at least one sensor capable of beingcoupled to the plasma processing system, and a controller coupled to theat least one sensor, wherein the controller provides at least onealgorithm for determining a state of the plasma processing system usingat least one signal generated from the at least one sensor andcontrolling a plasma processing system in order to suppress an arcingevent.

The present invention further provides a method for suppressing arcingin the plasma processing system utilizing the arc suppression systemcomprising the steps: measuring at least one signal related to theplasma processing system using at least one sensor; determining at leastone difference signal between the at least one signal and groundpotential; comparing the at least one difference signal to a targetdifference; and determining a state of the plasma processing system fromthe comparing.

The present invention further provides another method for suppressingarcing in the plasma processing system utilizing the arc suppressionsystem comprising the steps: measuring a first signal related to theplasma processing system using a first sensor; measuring a second signalrelated to the plasma processing system using a second sensor;determining a difference signal between the first signal and the secondsignal; comparing the difference signal to a target difference; anddetermining a state of the plasma processing system from the comparing.

It is another object of the present invention to provide a method forsuppressing arcing in the plasma processing system utilizing the arcsuppression system further comprising the step: controlling the plasmaprocessing system according to the state of the plasma processing systemin order to suppress an arcing event

BRIEF DESCRIPTION OF THE DRAWINGS

These and other advantages of the invention will become more apparentand more readily appreciated from the following detailed description ofthe exemplary embodiments of the invention taken in conjunction with theaccompanying drawings, where:

FIG. 1 shows an arc suppression system for plasma processing accordingto a preferred embodiment of the present invention;

FIG. 2 shows an arc suppression system for plasma processing accordingto an alternate embodiment of the present invention;

FIG. 3 shows an arc suppression system for plasma processing accordingto another embodiment of the present invention;

FIG. 4 shows an arc suppression system for plasma processing accordingto another embodiment of the present invention;

FIG. 5 shows an arc suppression system for plasma processing accordingto an additional embodiment of the present invention;

FIG. 6 shows an exploded view of a substrate holder incorporating an arcsuppression system according to an embodiment of the present invention;

FIG. 7A shows a top view of a substrate holder incorporating an arcsuppression system according to an embodiment of the present invention;

FIG. 7B shows a top view of a substrate holder incorporating an arcsuppression system according to another embodiment of the presentinvention;

FIG. 7C shows a top view of a substrate holder incorporating an arcsuppression system according to another embodiment of the presentinvention;

FIG. 7D shows a top view of a substrate holder incorporating an arcsuppression system according to another embodiment of the presentinvention;

FIG. 8A shows an exploded view of an antenna electrode and antenna leadaccording to an embodiment of the present invention;

FIG. 8B shows an exploded view of an antenna electrode and antenna leadaccording to another embodiment of the present invention;

FIG. 8C shows an exploded view of an antenna electrode and antenna leadaccording to another embodiment of the present invention;

FIG. 8D shows an exploded view of an antenna electrode and antenna leadaccording to another embodiment of the present invention;

FIG. 9 presents a flow diagram for an arc suppression procedureaccording to an embodiment of the present invention;

FIG. 10 shows an exemplary signal utilized by the arc suppression systemto determine a state of the processing plasma and control the plasmaprocessing system to avoid an arcing event according to an embodiment ofthe present invention; and

FIG. 11 presents a flow diagram for an arc suppression procedureaccording to another embodiment of the present invention.

DETAILED DESCRIPTION OF AN EMBODIMENT

According to an embodiment of the present invention, a plasma processingsystem 1 is depicted in FIG. 1 comprising a process reactor 10, asubstrate holder 20 to support a substrate 25, and an arc suppressionsystem 100, wherein the arc suppression system 100 comprises at leastone sensor 50 coupled to the process reactor 10, and a controller 55coupled to the at least one sensor 50. Moreover, the controller 55 iscapable of executing at least one algorithm for determining a state ofthe plasma processing system 1 using at least one signal generated fromthe at least one sensor 50 and controlling the plasma processing system1 in order to suppress an arcing event.

In one embodiment of the present invention, the at least one sensor 50can comprise at least one antenna, and an electrical measurement device56 coupled to each antenna. In an alternate embodiment, the at least oneantenna comprises at least one antenna electrode 52, and an antenna lead54 coupled to the at least one antenna electrode 52.

In the illustrated embodiment, plasma processing system 1, depicted inFIG. 1, utilizes a plasma for material processing. Desirably, plasmaprocessing system 1 comprises an etch chamber. Alternately, plasmaprocessing system 1 can comprise a deposition chamber such as a chemicalvapor deposition (CVD) system or a physical vapor deposition (PVD)system.

According to the illustrated embodiment of the present inventiondepicted in FIG. 2, plasma processing system 1 can comprise processreactor 10, substrate holder 20, upon which a substrate 25 to beprocessed is affixed, gas injection system 40, and vacuum pumping system58. Substrate 25 can be, for example, a semiconductor substrate, awafer, or a liquid crystal display (LCD). Process reactor 10 can be, forexample, configured to facilitate the generation of plasma in processingregion 45 adjacent a surface of substrate 25, wherein plasma is formedvia collisions between heated electrons and an ionizable gas. Forexample, an ionizable gas or mixture of gases can be introduced via gasinjection system 40, and the process pressure can be adjusted usingvacuum pumping system 58. Desirably, plasma is utilized to creatematerials specific to a pre-determined materials process, and to aideither the deposition of material to substrate 25 or the removal ofmaterial from the exposed surfaces of substrate 25.

For example, the substrate 25 can be affixed to the substrate holder 20via an electrostatic clamping system 28. Furthermore, substrate holder20 can further include a cooling system including a re-circulatingcoolant flow that receives heat from substrate holder 20 and transfersheat to a heat exchanger system (not shown), or when heating, transfersheat from the heat exchanger system. Moreover, gas can be delivered tothe back-side of the substrate via a backside gas system 26 to improvethe gas-gap thermal conductance between substrate 25 and substrateholder 20. Such a system can be utilized when temperature control of thesubstrate is required at elevated or reduced temperatures. For example,temperature control of the substrate can be useful at temperatures inexcess of the steady-state temperature achieved due to a balance of theheat flux delivered to the substrate 25 from the plasma and the heatflux removed from substrate 25 by conduction to the substrate holder 20.In other embodiments, heating elements, such as resistive heatingelements, or thermo-electric heaters/coolers can be included.

In the exemplary embodiment shown in FIG. 2, substrate holder 20 canfurther serve as an electrode through which RF power is coupled toplasma in processing region 45. For example, substrate holder 20 can beelectrically biased at a RF voltage via the transmission of RF powerfrom RF generator 30 through impedance match network 32 to substrateholder 20. The RF bias can serve to heat electrons and, thereby, formand maintain plasma. In this configuration, the system can operate as areactive ion etch (RIE) reactor, wherein the chamber and upper gasinjection electrode serve as ground surfaces. A typical frequency forthe RF bias can range from 1 MHz to 100 MHz and is preferably 13.56 MHz.RF systems for plasma processing are well known to those skilled in theart.

Alternately, RF power can be applied to the substrate holder electrodeat multiple frequencies. Furthermore, impedance match network 32 canserve to maximize the transfer of RF power to plasma in process reactor10 by minimizing the reflected power. Match network topologies (e.g.L-type, π-type, T-type, etc.) and automatic control methods are wellknown to those skilled in the art.

With continuing reference to FIG. 2, process gas can be introduced toprocessing region 45 through gas injection system 40. Process gas can,for example, comprise a mixture of gases such as Argon, CF₄ and O₂, orArgon, C₄F₈ and O₂ for oxide etch applications, or other chemistriessuch as O₂/CO/Ar/C₄F₈, O₂/CO/AR/C₅F₈, O₂/CO/Ar/C₄F₆, O₂/Ar/C₄F₆, N₂/H₂.Gas injection system 40 can comprise a showerhead, wherein process gasis supplied from a gas delivery system (not shown) to the processingregion 45 through a gas injection plenum (not shown), a series of baffleplates (not shown) and a multi-orifice showerhead gas injection plate(not shown). Gas injection systems are well known to those of skill inthe art.

Vacuum pump system 58 can, for example, include a turbo-molecular vacuumpump (TMP) capable of a pumping speed up to 5000 liters per second (andgreater) and a gate valve for throttling the chamber pressure. Inconventional plasma processing devices utilized for dry plasma etching,a 1000 to 3000 liter per second TMP is generally employed. TMPs areuseful for low pressure processing, typically less than 50 mTorr. Athigher pressures, the TMP pumping speed falls off dramatically. For highpressure processing (i.e. greater than 100 mTorr), a mechanical boosterpump and dry roughing pump can be used. Furthermore, a device formonitoring chamber pressure (not shown) is coupled to the processreactor 10. The pressure measuring device can be, for example, a Type628B Baratron absolute capacitance manometer commercially available fromMKS Instruments, Inc. (Andover, Mass.).

For example, controller 55 can comprise a microprocessor, memory, and adigital I/O port capable of generating control voltages sufficient tocommunicate and activate inputs to plasma processing system 1 as well asmonitor outputs from plasma processing system 1. Moreover, controller 55is further coupled to and exchanges information with RF generator 30,impedance match network 32, gas injection system 40, vacuum pump system58, backside gas delivery system 26, electrostatic clamping system 28,and sensor 50. A program stored in the memory is utilized to activatethe inputs to the aforementioned components of a plasma processingsystem 1 according to a stored process recipe. One example of controller55 is a DELL PRECISION WORKSTATION 610™, available from DellCorporation, Dallas, Tex. Alternately, controller 55 can comprise aDigital Signal Processor (DSP).

In the exemplary embodiment shown in FIG. 3, the plasma processingsystem 1 can further comprise a magnetic field system 60. For example,magnetic system 60 can comprise a stationary or either a mechanically orelectrically rotating DC magnetic field system, in order to potentiallyincrease plasma density and/or improve plasma processing uniformity.Moreover, controller 55 can be coupled to a rotating magnetic fieldsystem in order to regulate the speed of rotation and field strength.The design and implementation of a rotating magnetic field is well knownto those skilled in the art.

In the exemplary embodiment shown in FIG. 4, the plasma processingsystem 1 of FIGS. 1 and 2 can further comprise an upper electrode 70 towhich RF power can be coupled from RF generator 72 through impedancematch network 74. A typical frequency for the application of RF power tothe upper electrode can range from 10 MHz to 200 MHz and is preferably60 MHz. Additionally, a typical frequency for the application of powerto the lower electrode can range from 0.1 MHz to 30 MHz and ispreferably 2 MHz. Moreover, controller 55 is coupled to RF generator 72and impedance match network 74 in order to control the application of RFpower to upper electrode 70. The design and implementation of an upperelectrode is well known to those skilled in the art.

In the exemplary embodiment shown in FIG. 5, the plasma processingsystem of FIGS. 1 and 2 can, for example, further comprise an inductivecoil 80 to which RF power is coupled via RF generator 82 throughimpedance match network 84. RF power is inductively coupled frominductive coil 80 through dielectric window (not shown) to plasmaprocessing region 45. A typical frequency for the application of RFpower to the inductive coil 80 can range from 10 MHz to 100 MHz and ispreferably 13.56 MHz. Similarly, atypical frequency for the applicationof power to the chuck electrode can range from 0.1 MHz to 30 MHz and ispreferably 13.56 MHz. In addition, a slotted Faraday shield (not shown)can be employed to reduce capacitive coupling between the inductive coil80 and plasma. Moreover, controller 55 is coupled to RF generator 82through impedance match network 84 in order to control the applicationof power to inductive coil 80. In an alternate embodiment, inductivecoil 80 can be a “spiral” coil or “pancake” coil in communication withthe plasma processing region from above as in a transformer coupledplasma (TCP) reactor. The design and implementation of an inductivelycoupled plasma (ICP) source and/or transformer coupled plasma (TCP)source is well known to those skilled in the art.

Alternately, the plasma can be formed using electron cyclotron resonance(ECR). In yet another embodiment, the plasma is formed from thelaunching of a Helicon wave. In yet another embodiment, the plasma isformed from a propagating surface wave. Each plasma source describedabove is well known to those skilled in the art.

As discussed above, arc suppression system 100 comprises at least onesensor 50 coupled to the process reactor 10, and controller 55 coupledto the at least one sensor 50, wherein controller 55 is capable ofexecuting at least one algorithm for determining a state of plasmaprocessing system 1 using at least one signal generated from the atleast one sensor 50 and controlling a plasma processing system 1 inorder to suppress an arcing event. In the following discussion, the arcsuppression system 100 is discussed in greater detail.

Referring now to FIG. 6, an exploded view of a cross-section ofsubstrate holder 20 is presented. In general, the substrate holder 20can comprise an outer shield 122, an isolation ring 124, a RF biasableelectrode 126 underlying substrate 25 and a focus ring 128 surroundingthe substrate 25. The outer shield 122 can be, for example, anelectrically grounded conductive element comprising a material such asaluminum with or without surface anodization and/or a surface coating(e.g. Y₂O₃). The isolation ring 124 provides electrical insulationbetween the RF biasable electrode 126 and the outer shield 122, and itcan, for example, comprise a dielectric material such as, for example,alumina, quartz, etc. The RF biasable electrode 126 can be biased withRF energy from a RF generator such as the RF generator depicted in FIGS.2 through 5. Alternately, RF biasable electrode 126 can be grounded. TheRF biasable electrode 126 can comprise a conductive material such asaluminum. The focus ring 128 generally serves to affect the etch ordeposition processes occurring at the periphery of substrate 25 in amanner that permits uniform processing of substrate 25 over the entiretyof its surface. The focus ring 128 can comprise a material such assilicon, carbon, silicon carbide, etc.

In addition to the above identified features, an electrostatic clampingdevice 130 can be formed within the upper surface of the RF biasableelectrode 126. The electrostatic clamping device 130 comprises a clampelectrode 132 embedded within an insulation layer 134, wherein the clampelectrode 132 is biased with a DC voltage supplied from a high voltageDC voltage source (identified as part of electrostatic clamping system28 in FIGS. 2 through 5). In conventional electrostatic clampingdevices, the clamp electrode 132 is fabricated from a material such ascopper, nickel, chromium, aluminum, iron, tungsten and alloys thereof,and the insulation layer 134 is fabricated from a ceramic, glass or hightemperature polymer material such as alumina Al₂O₃, quartz SiO₂,aluminum nitride AlN, Si₃N₄, ZrO₂, silicon carbide SiC, boron nitrideBN, glass ceramic, and polyimide materials. Methods for fabricating anelectrostatic clamping device 130 comprising a clamp electrode 133 andceramic layer 134 and the means by which a high voltage, DC signal iscoupled to clamp electrode 132 are well known to those skilled in theart of electrostatic chucks.

As depicted in FIG. 6 (cross-sectional, side view) as well as FIG. 7A(top view), at least one sensor 50 is coupled to substrate holder 20.For example, the at least one sensor 50 can comprise at least oneantenna electrode 52, at least one antenna lead 54, and at least oneelectrical measurement device 56. The at least one antenna electrode 52can be embedded within the ceramic layer 134 proximate an upper surfacethereof, wherein at least one antenna lead 54 extends through openings136 in clamp electrode 132 and couples to the at least one antennaelectrode 52. The at least one antenna lead 54, that is coupled to theat least one antenna electrode 52, can be further coupled to at leastone electrical measurement device 56. The at least one sensor 50measures at least one electrical signal that is, in turn, coupled tocontroller 55. In an alternate embodiment, as shown in FIG. 7B, the atleast one antenna electrode 52 can be elliptical. In an alternateembodiment, as shown in FIG. 7C, the at least one antenna electrode 52can be “kidney-shaped.” In an alternate embodiment, the at least oneelectrode 52 can be rectangular. Alternate embodiments, such as shown inFIG. 7D, can vary the arrangement of the antenna electrodes 52 to placethem in various locations. However, it should be appreciated that anyarrangement of antennas and any number of antennas can be used accordingto the present invention.

In reference to clamp electrode 132, the at least one antenna electrode52 and the conductive element(s) of the at least one antenna lead 54 canbe fabricated from copper or a like conducting material. In a preferredembodiment, the at least one antenna lead 54 is shielded using an outerconductive shield and insulated from the clamp electrode 132 and RFbiasable electrode 126.

FIG. 8A provides an exploded view of an antenna electrode 52 and antennalead 54 embedded within an electrostatic clamping device 130 and RFbiasable electrode 126. The antenna lead 54 comprises an innerconductive element 542, an inner dielectric element 544, an outerconductive element 546, and an outer dielectric element 548. The innerdielectric element 544 surrounds the inner conductive element 542 andinsulates the inner conductive element 542 from an outer conductiveelement 546. The outer conductive element 546 surrounds the innerdielectric element 544 and shields the inner conductive element 542. Theouter dielectric element 548 surrounds the outer conductive element 546and insulates the outer conductive element 546 from the RF biasableelectrode 126. Desirably, the outer conductive element 546 is coupled toelectrical ground. In an alternate embodiment, as shown in FIG. 8B, theupper surface of antenna electrode 52 is not coplanar with the uppersurface of ceramic layer 134.

The electrostatic clamping device 130, comprises clamp electrode 132,insulation layer 134, and at least one embedded antenna electrodes 52with at least one antenna leads 54. Such an electrostatic clampingdevice 130 can be fabricated using sintering techniques, castingtechniques and/or thin film forming techniques (such as, for example,chemical vapor deposition (CVD)), which have become standards in theindustry and are now well known to those skilled in the art ofelectrostatic chuck fabrication. Exemplary techniques are disclosed inU.S. Pat. Nos. 5,539,179, 5,625,526 and 5,701,228 (all three areassigned to Tokyo Electron Limited); each of which is incorporatedherein by reference in their entirety.

As shown in FIG. 6, at least one electrical measurement device 56 isconnected to the at least one antenna lead to perform, for example, a RFvoltage measurement. Each electrical measurement device 56 can be, forexample, a (high impedance) Tektronix P6245 1.5 GHz 10X Active Probemanufactured by Tektronix. The signal produced by the at least onesensor 50 can be input to the controller 55 such as, for example, adigital signal processor (DSP) using, for example, an analog-to-digital(A/D) converter.

Although antenna electrodes 52 and antenna leads 54 have been shown, inFIGS. 6 and 8A–8D, to be fabricated within the electrostatic clampingdevice 130 and RF biasable electrode 126, the antenna electrodes 52 andantenna leads 54 can be fabricated within other structures such as, forexample, the focus ring 128, the dielectric ring 124, the outer shield122, a shield ring, a chamber wall, a chamber liner, etc. For example,FIGS. 8C and 8D present a consumable electrode 570 embedded within afocus ring 560 resting atop RF biasable electrode 126, wherein theconsumable electrode 570 can comprise a convex surface 580 forelectrically coupling the consumable electrode 570 to the antennaelectrode 52. In FIG. 8C, the consumable electrode 570 is coplanar withthe upper surface of the focus ring 560, and in FIG. 8D the consumableelectrode 570 is not coplanar with the upper surface of the focus ring560. In conventional systems, the focus ring 560 is designed forrepeatable replacement on the RF biasable electrode 126 and, therefore,consumable electrode 570 can be consistently coupled to antennaelectrode 52. The focus ring 128 or 560 can, for example, comprise atleast one of silicon, silicon carbide, alumina, or quartz. In addition,consumable electrode 570 can, for example, comprise doped silicon or anembedded, conductive material such as tungsten.

Methods of using an arc suppression system are now discussed. FIG. 9presents a flow diagram for an arc suppression procedure according to anembodiment of the present invention. Procedure 600 begins with 610wherein at least one signal is measured using the at least one sensor.For example, the at least one sensor can comprise at least one antennaelectrode coupled to at least one antenna lead coupled to at least oneelectrical measurement device. The signal can be, for example, a timevarying voltage signal or a time varying voltage amplitude measuredusing, for example, a voltage probe. In an alternate embodiment, thesignal measured by the sensor can be filtered using a low-pass,high-pass, and/or band-pass filter. The filtered signal can be, forexample, a filtered time varying voltage signal or a filtered timevarying voltage amplitude. In 620, the measured signal and/or filteredsignal is compared to a reference to determine a difference signal. Forexample, a ground potential or another potential point in the system canbe used as the reference. The difference signal can be, for example, thedifference between the instantaneous value of the signal measured at aninstant in time and electrical ground, the amplitude of the measuredsignal, the difference between the instantaneous value of the filteredsignal measured at an instant in time and electrical ground, or theamplitude of the filtered signal. For example, the difference signal canbe determined from the operation of subtraction.

In 630, the difference signal is compared to a target difference asshown in FIG. 10. FIG. 10 presents an exemplary difference signal 634plotted in time, with a target difference 632 (indicated by the dashedline) overlaid. By inspection, the time 636 in which the measureddifference signal exceeds the target difference is indicated by thearrow. In 640, a state of the plasma processing system is determinedusing the comparison in 630. For example, if the difference signalexceeds the target difference, then the probability for an arcing eventis relatively high; and if the at least one difference signal does notexceed the target difference, then the probability for an arcing eventis relatively low. Based on the determination of 640, a decision forpresenting an arc alarm is made in 650. For example, if the probabilityfor an arcing event is relatively high, then an operator is notified in660, and if the probability for an arcing event is relatively low, thenprocessing continues in 670.

Furthermore, in the event of an arc alarm, the process can be controlledfollowing notification of an operator in 660. In 680, a decision is madeto control the process including continuing the process in 670,discontinuing the process in 690, and modifying the process in 695. Inan alternate embodiment, the decision to control the process in 680 isperformed concurrently with the notification of an operator in 660 bythe controller. In an alternate embodiment, the decision to control theprocess in 680 is performed concurrently with simply a logging of theprobability for an arcing event in 660. In an alternate embodiment, thedecision to control the process in 680 is performed with no notificationof an operator in 660. In 695, the process can be modified by adjustinga process parameter. For example, the process parameter can include theprocess pressure, substrate holder RF bias, electrostatic clampelectrode bias, backside gas pressure, process gas flow rate(s), etc.

FIG. 11 presents a flow diagram for an arc suppression procedureaccording to an alternate embodiment of the present invention. Procedure700 begins with 710 wherein a first signal related to the plasmaprocessing system is measured using a first sensor. For example, thefirst sensor can comprise a first antenna electrode coupled to a firstantenna lead coupled to a first electrical measurement device. The firstsignal can be, for example, derived from a first region of thesubstrate. The first signal can be, for example, a time varying voltagesignal or a time varying voltage amplitude measured using, for example,a voltage probe. In an alternate embodiment, the first signal measuredby the first sensor can be filtered using a low-pass, high-pass, and/orband-pass filter. The filtered signal can be, for example, a filteredtime varying voltage signal or a filtered time varying voltageamplitude.

In 720, a second signal related to the plasma processing system ismeasured using a second sensor. For example, the second sensor cancomprise a second antenna electrode coupled to a second antenna leadcoupled to a second electrical measurement device. The second signal canbe, for example, derived from a second region of the substrate. Thesecond signal can be, for example, a time varying voltage signal or atime varying voltage amplitude measured using, for example, a voltageprobe. In an alternate embodiment, the second signal measured by thesecond electrical sensor can be filtered using a low-pass, high-pass,and/or band-pass filter. The filtered signal can be, for example, afiltered time varying voltage signal or a filtered time varying voltageamplitude. Preferably, the acquisition of the first signal and thesecond signal is performed at the same instant in time.

In one embodiment, the first signal corresponds to a location proximatethe substrate center and the second signal corresponds to a locationproximate the substrate edge. In another embodiment, the first signalcorresponds to a location proximate the substrate edge and the secondsignal corresponds to a location proximate the focus ring.

In another embodiment, the first signal corresponds to a first locationand a first time for measurement, and the second signal corresponds tothe first location and a second time for the measurement. Themeasurement of a first signal and a second signal at the same location;however, different time, can permit checking the rate of change of themeasurement.

In 730, a difference signal is determined by comparing the first signaland the second signal at each instant of time. The difference signal canbe, for example, the difference between the instantaneous value of thefirst signal and the instantaneous value of the second signal, theamplitude of the first signal and the amplitude of the second signal,the difference between the instantaneous value of the filtered firstsignal and the instantaneous value of the filtered second signal, or theamplitude of the filtered first-signal and the amplitude of the filteredsecond signal.

In 740, the difference signal is compared to a target difference asshown in FIG. 10. FIG. 10 presents an exemplary difference signal 634plotted in time, with a target difference 632 (indicated by the dashedline) overlaid. By inspection, the time 636 in which the measureddifference signal exceeds the target difference is indicated by thearrow. In 750, a state of the plasma processing system is determinedusing the comparison in 740. For example, if the difference signalexceeds the target difference, then the probability for an arcing eventis relatively high; and if the difference signal does not exceed thetarget difference, then the probability for an arcing event isrelatively low. Based on the determination of 750, a decision forpresenting an arc alarm is made in 760. For example, if the probabilityfor an arcing event is relatively high, then an operator is notified in770, and if the probability for an arcing event is relatively low, thenprocessing continues in 780.

When two or more signals are utilized, additional information can bepresented. For example, the location for the highest probability forarcing can be determined by monitoring those regions where the magnitudeof the difference signal is greatest.

Furthermore, in the event of an arc alarm, the process can be controlledfollowing notification of an operator in 770. In 790, a decision is madeto control the process including continuing the process in 780,discontinuing the process in 800 and modifying the process in 810. In analternate embodiment, the decision to control the process in 790 isperformed concurrently with the notification of an operator in 770 bythe controller. In an alternate embodiment, the decision to control theprocess in 790 is performed concurrently with simply a logging of theprobability for an arcing event in 770. In an alternate embodiment, thedecision to control the process in 790 is performed with no notificationof an operator in 770. In 810, the process can be modified by adjustinga process parameter. For example, the process parameter can include theprocess pressure, substrate holder RF bias, electrostatic clampelectrode bias, backside gas pressure, process gas flow rate(s), etc.

Although only certain exemplary embodiments of this invention have beendescribed in detail above, those skilled in the art will readilyappreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention.

1. A plasma processing system, comprising: a process reactor configuredto facilitate formation of plasma; and an arc suppression system coupledto said process reactor, said arc suppression system comprising at leastone sensor configured to produce at least one signal related to saidplasma; and a controller coupled to said at least one sensor, whereinsaid controller is configured to determine a state of a probability ofoccurrence of arcing in said plasma processing system using said atleast one signal and to control said plasma processing system accordingto said state to reduce the probability of occurrence of an arcingevent.
 2. The plasma processing system as recited in claim 1, whereinsaid at least one sensor comprises at least one antenna embedded withinat least one of a substrate holder, a chamber wall and a chamber liner.3. The plasma processing system as recited in claim 2, wherein said atleast one antenna comprises at least one antenna electrode and anantenna lead coupled to each antenna electrode of the at least oneantenna electrode.
 4. The plasma processing system as recited in claim3, wherein said antenna lead comprises an inner conductive element andan inner dielectric element.
 5. The plasma processing system as recitedin claim 4, wherein said antenna lead further comprises an outerconductive element and an outer dielectric element.
 6. The plasmaprocessing system as recited in claim 2, further comprising anelectrical measurement device configured to connect to said at least oneantenna.
 7. The plasma processing system as recited in claim 2, said atleast one antenna being embedded within said substrate holder whichcomprises at least one of a RF biasable electrode, an electrostaticclamping device, an outer shield, an isolation ring, a focus ring, adielectric ring, and a shield ring.
 8. The plasma processing system asrecited in claim 2, wherein said substrate holder comprises at least oneof an electrostatic clamping system and a backside gas system.
 9. Theplasma processing system as recited in claim 6, wherein the electricalmeasurement device comprises a voltage probe.
 10. The plasma processingsystem as recited in claim 1, wherein said at least one signal relatedto said plasma is at least one of a time varying voltage signal and atime varying voltage amplitude.
 11. The plasma processing system asrecited in claim 1, wherein said at least one signal related to saidplasma comprises a filtered signal.
 12. The plasma processing system asrecited in claim 11, wherein said filtered signal is derived from saidat least one signal using at least one of a low-pass filter, a high-passfilter, and a band-pass filter.
 13. The plasma processing system asrecited in claim 1, wherein said at least one sensor comprises aplurality of sensors and said controller is configured to determine astate of a probability of occurrence of arcing at different regions insaid plasma processing system.
 14. The plasma processing system asrecited in claim 1, wherein said controlling said plasma processingsystem according to said state of said plasma in order to suppress thearcing event comprises performing at least one of alerting an operator,continuing a process, modifying a process and discontinuing a process.15. An arc suppression system comprising: at least one sensor configuredto couple to a plasma processing system; and a controller configured toexecute at least one algorithm for determining a state of a probabilityof occurrence of arcing in said plasma processing system using said atleast one signal related to said plasma processing system andcontrolling said plasma processing system according to said state inorder to reduce the probability of occurrence of an arcing event. 16.The arc suppression system as recited in claim 15, wherein said at leastone sensor comprises at least one antenna embedded within at least oneof a substrate holder, a chamber wall and a chamber liner.
 17. Theplasma processing system as recited in claim 16, wherein said at leastone antenna comprises at least one antenna electrode and an antenna leadcoupled to each antenna electrode of the at least one antenna electrode.18. The arc suppression system as recited in claim 17, wherein saidantenna lead comprises an inner conductive element and an innerdielectric element.
 19. The arc suppression system as recited in claim18, wherein said antenna lead further comprises an outer conductiveelement and an outer dielectric element.
 20. The arc suppression systemas recited in claim 16, further comprising an electrical measurementdevice configured to connect to said at least one antenna.
 21. The arcsuppression system as recited in claim 15, wherein said at least oneantenna embedded with said substrate holder comprises at least oneantenna embedded in at least one of a RF biasable electrode, anelectrostatic clamping device, an outer shield, an isolation ring, afocus ring a dielectric ring, and a shield ring.
 22. The arc suppressionsystem as recited in claim 16, wherein said substrate holder comprisesat least one of an electrostatic clamping system and a backside gassystem.
 23. The arc suppression system as recited in claim 20, whereinsaid electrical measurement device comprises a voltage probe.
 24. Thearc suppression system as recited in claim 15, wherein said at least onesignal related to said plasma is at least one of a time varying voltagesignal and a time varying voltage amplitude.
 25. The arc suppressionsystem as recited in claim 15, wherein said at least one signal relatedto said plasma comprises a filtered signal.
 26. The arc suppressionsystem as recited in claim 25, further comprises at least one of alow-pass filter, a high-pass filter, and a band-pass filter configuredto derive said filtered signal from said at least one signal.
 27. Thearc suppression system as recited in claim 15, wherein said at least onesensor comprises a plurality of sensors and said controller isconfigured to determine a state of a probability of occurrence of arcingat different regions in said plasma processing system.
 28. The arcsuppression system as recited in claim 15, wherein said controlling saidplasma processing system according to said state of said plasma in orderto suppress an arcing event comprises performing at least one ofalerting an operator, continuing a process, modifying a process anddiscontinuing a process.
 29. A method for suppressing arcing in a plasmaprocessing system utilizing an arc suppression system comprising atleast one sensor coupled to said plasma processing system, and acontroller coupled to said at least one sensor, the method comprising:measuring at least one signal related to said plasma processing systemusing said at least one sensor; determining at least one differencesignal between said at least one signal and a reference signal;comparing said at least one difference signal to a target difference;determining a state of a probability of occurrence of arcing in saidplasma processing system from said comparing; and controlling saidplasma processing system in order to reduce the probability ofoccurrence of an arcing event, wherein said at least one signal ismeasured using at least one sensor that comprises at least one antennaembedded within at least one of a substrate holder, a chamber wall and achamber liner.
 30. The method as recited in claim 29, wherein saidmeasuring further comprises filtering said at least one signal.
 31. Themethod as recited in claim 30, wherein said filtering comprises using atleast one of a low-pass filter, a high-pass filter, and a band-passfilter.
 32. The method as recited in claim 30, wherein said filteringprovides at least one of a filtered time varying signal and a filteredtime varying amplitude.
 33. The method as recited in claim 29, whereinsaid determining at least one difference signal between said at leastone signal and said reference signal comprises subtracting saidreference signal from said at least one signal.
 34. The method asrecited in claim 29, wherein said at least one difference signalcomprises at least one of a difference between an instantaneous value ofsaid at least one signal measured at an instant in time and saidreference signal, an amplitude of said at least one signal and saidreference signal, an instantaneous value of a filtered said at least onesignal measured at an instant in time and said reference signal, andamplitude of a filtered said at least one signal and said referencesignal.
 35. The method as recited in claim 29, wherein said measuringcomprises measuring a plurality of signals at different regions of theplasma processing system using a plurality of respective sensors, andsaid determining comprises determining a state of a probability of anoccurrence of arcing at said different regions in said plasma processingsystem.
 36. The method as recited in claim 29, wherein said probabilityfor the occurrence of arcing in said plasma processing system comprisesat least one of a high probability and a low probability.
 37. The methodas recited in claim 29, wherein said method further comprisescontrolling said plasma processing system according to said state ofsaid plasma processing system in order to suppress an arcing event. 38.The method as recited in claim 33, wherein said controlling comprises atleast one of notifying an operator, continuing a process, discontinuinga process, and modifying a process.
 39. The method as recited in claim38, wherein said modifying a process comprises adjusting at least one ofa process pressure, a substrate holder RF bias, an electrostatic clampelectrode bias, a backside gas pressure, and a process gas flow rate.40. The method as recited in claim 29, wherein said reference signalcomprises a ground potential.
 41. A method for suppressing arcing in aplasma processing system utilizing an arc suppression system comprisingat least one sensor coupled to said plasma processing system, and acontroller coupled to said at least one sensor, the method comprising:measuring a first signal related to said plasma processing system usinga first sensor; measuring a second signal related to said plasmaprocessing system using a second sensor; determining a difference signalbetween said first signal and said second signal; comparing saiddifference signal to a target difference; determining a state of aprobability of occurrence of arcing in said plasma processing systembased on said comparing; and controlling said plasma processing systemin order to reduce the probability of occurrence of an arcing event. 42.The method as recited in claim 41, wherein said first signal is measuredusing at least one sensor that comprises at least one antenna embeddedwithin at least one of a substrate holder, a chamber wall and a chamberliner.
 43. The method as recited in claim 41, wherein said measuring thefirst signal further comprises filtering said first signal.
 44. Themethod as recited in claim 43, wherein said filtering comprises using atleast one of a low-pass filter, a high-pass filter, and a band-passfilter.
 45. The method as recited in claim 43, wherein said filteringprovides at least one of a first filtered time varying signal and afirst filtered time varying amplitude.
 46. The method as recited inclaim 41, wherein said second signal is measured using at least onesensor that comprises at least one antenna embedded within at least oneof a substrate holder, a chamber wall and a chamber liner.
 47. method asrecited in claim 41, wherein said measuring the second signal furthercomprises filtering said second signal.
 48. The method as recited inclaim 47, wherein said filtering comprises using at least one of alow-pass filter, a high-pass filter and a band-pass filter.
 49. Themethod as recited in claim 47, wherein said filtering provides at leastone of a second filtered time varying signal and a second filtered timevarying amplitude.
 50. The method as recited in claim 41, wherein saiddetermining a difference signal between said first signal and saidsecond signal comprises subtracting said first signal from said secondsignal.
 51. The method as recited in claim 41, wherein said determiningcomprises determining a state of the probability for the occurrence ofarcing at different regions in said plasma processing system.
 52. Themethod as recited in claim 51, wherein said probability for theoccurrence of arcing in said plasma processing system comprises at leastone of a high probability and a low probability.
 53. The method asrecited in claim 43, wherein said method further comprises controllingsaid plasma processing system according to said state of said plasmaprocessing system in order to suppress an arcing event.
 54. The methodas recited in claim 53, wherein said controlling comprises at least oneof notifying an operator, continuing a process, discontinuing a process,and modifying a process.
 55. The method as recited in claim 54, whereinsaid modifying a process comprises adjusting at least one of a processpressure, a substrate holder RF bias, an electrostatic clamp electrodebias, a backside gas pressure, and a process gas flow rate.
 56. Themethod as recited in claim 41, wherein said measuring a first signal andsaid measuring a second signal are performed at substantially the sametime.
 57. The method as recited in claim 41, wherein said measuring afirst signal and said measuring a second signal are performed atsubstantially different times.
 58. The method as recited in claim 41,wherein said measuring a first signal corresponds to a first locationand said measuring a second signal corresponds to a second location. 59.The method as recited in claim 58, wherein said first location comprisesat least one of a substrate center, a substrate edge, and a focus ring;and said second location comprises at least one of a substrate center, asubstrate edge, and a focus ring.
 60. A plasma processing system,comprising: a plasma reactor configured to facilitate formation ofplasma; and means for arc suppression coupled to plasma reactor, saidmeans for arc suppression comprising means for producing at least onesignal related to said plasma; and means for controlling coupled to saidat least one sensor, wherein said means for controlling determines astate of a probability of occurrence of arcing in said plasma processingsystem using said at least one signal and controls said plasmaprocessing system according to said state to reduce the probability ofoccurrence of an arcing event.
 61. The plasma processing system asrecited in claim 60, wherein said means for producing at least onesignal comprises at least one antenna embedded within at least one of asubstrate holder, a chamber wall and a chamber liner.
 62. The plasmaprocessing system as recited in claim 60, further comprising anelectrical measurement device.
 63. The plasma processing system asrecited in claim 62, wherein the electrical measurement device comprisesa voltage probe.
 64. The plasma processing system as recited in claim60, further comprising housing means for protecting the means forproducing the at least one signal from the plasma of the plasma reactor.